Quote - All objects are parented to the "floor_1" object but ...

... unfortunately, the origin of the separate objects is not at the bottom of the object so that scaling the main parent will not work as desired.

Each object would need to be scaled and repositioned separately.

Sorry 'bout that.

Hu???

If all the objects are parented to the floor it's easy peasy! Make sure the floor is is at zero altitude. Parent the floor to MinFig. Scale MinFig to 130%. Everything should scale with it in proportion. Should work for almost anything.

Quote - I don't think scaling the whole scene will work as I want it too sadly...

Now I'm confused. What do you mean by "whole scene", the Big Office, no? I thought that is what you wanted to do, scale the Big Office up by 130%? What's the problem, why won't scaling the Big Office by 130% achieve your desired aim?